Flyback converter topology is the basic power conversion scheme for DC-DC and AC-DC isolated converters for high voltage and low output current requirements. Mostly these are limited to around 200 watts output power and multiple output requirements. However, in a normal flyback converter, the stresses on the components are higher due to parasitics associated with magnetics. A hard switched flyback converter invariably demands an RCD snubber to protect the main switching device, be it a metal-oxide-semiconductor field-effect transistor (MOSFET) or a bipolar transistor. This is mainly due to leakage inductance associated with the power transformer. MOSFET is widely used for high frequency applications in the range of 100 KHZ. In low input voltage applications, input currents drawn are fairly large. Switching losses increase with the operating frequency. Therefore, to achieve higher frequency, it is mandatory to adopt soft switching techniques. Soft switching mitigates the switching losses and hence allows high frequency operation.
Most of the existing soft switching techniques use an additional auxiliary switch and its drive control to achieve soft switching. Additional components and drive control are of a higher complexity and cost.